1. Field of the Invention
The present invention relates to a method for forming printing inspection data used in a printing inspection apparatus for inspecting the printed state of a cream solder printed on a board.
2. Description of the Related Art
In mounting electronic parts, cream solder is applied to the surface of a board before the electronic parts are mounted on the board. As a method for applying the cream solder, a screen printing method is widely employed. After a printing step, a printing inspection for inspecting the printed state of the cream solder is carried out. This printing inspection decides whether or not the cream solder is properly printed on a printing position by picking-up the image of the board after the screen printing by a camera and processing the image of the picked-up result. Then, before the printing inspection, inspecting data for instructing the printing position on which the cream solder of the board to be inspected is printed is inputted to a printing inspection apparatus.
The inspecting data has been hitherto formed by various kinds of methods. For example, a variety of kinds of methods include a method of using mask data showing the forms of pattern holes of a mask plate used for printing, a method of obtaining electrode positions from the mounting data of a board, a method of obtaining these data from an actual mask plate used for printing, etc. The method for using the mask plate of these methods serves to detect the opening positions or the forms of the pattern holes by a method of recognizing images or the like. In this method, the inspecting data can be advantageously formed on the spot of production even when the mask data or the mounting data is not given.
However, the method of using the mask plate has problems as described below. When the opening parts of the mask plate are detected by recognizing the images, the image pick-up visual field of a camera used for picking-up images is ordinarily smaller than the size of the mask plate. In order to recognize an image, the image needs to be picked up a plurality of times while the image pick-up visual field of the camera is moved on the mask plate. Then, recognized results obtained by a plurality of images are combined together to detect the position or the form of each opening part on the mask plate.
However, at this time, each opening part is not necessarily incorporated in any of the image pick-up visual fields in a complete form, and the opening parts may sometimes partly protrude from one image pick-up visual field. In such a case, it has been hitherto difficult to precisely obtain the positions or the forms of the opening parts, so that the simple and efficient formation of the inspecting data using the mask plate has been prevented.